U.S. aviation officials believe a bird strike may have led to the deadly crash of an Ethiopian Airlines Boeing 737 Max in March, according to a person familiar with the matter. Boeing shares were up 1.3% in morning trading. The fast-selling Boeing 737 Max airplanes have been grounded since shortly after that accident, which came less than five months after a similar crash in Indonesia. Together, the two crashes killed 346 people. Crash investigators have indicated that bad sensor data triggered… (www.cnbc.com) Más...

I'll get blasted for this. The data showed that AOA was reading correctly, then suddenly went to the limit. That triggered the incident. Could a bird striking an AOA sensor do this? Possible. Should it cause a crash? No. Just like pitot icing should not cause a crash. Surely this must have been taken into consideration during the design. Reading the comments, I think people are saying they are blaming everything on a bird. I look at it as a clue as to what might have happened, should have been known as a possibility during design, and therefore puts more blame on the design.

Agree, the incorrect data from the AoA input started the sequence of events. This invalid input in itself should not have escalated into the critical event that it became. The bird strike scenario is one of many possible causes for the invalid data, but possibly the best case scenario for Boeing. It seems like a leak / speculation to help the share price rather than informed knowledge from the investigation. Actually a bird strike was my initial thought, but then I read about other more serious possibilities. In the Ethiopian case it seems unlikely that a faulty AoA vane was the cause, although this does seem to be a line of enquiry for the Lion Air investigation. Another scenario is that it was an electromechanical failure downstream of the sensor. The data released appears to suggest an instantaneous change in the AoA position. Intuition suggests that a bird strike would lead to a gradual change in position and maybe not a steady value. An alternative view is a change in value of one bit in the digital representation of the analogue AoA value. This hypothesis is explained nicely by Simon on Aviation Herald. What could cause an intermittent fluctuation in a data value? Maybe that is where the investigators need to analyse the infamous swarm which is rumoured to plague Boeing built aircraft. This leads to another area of concern, that of the alleged failings in quality control at certain manufacturing facilities. When it comes to ungrounding, signing off an act of God (aka bird strike) might be much quicker and less costly than a fleet wide inspection of all flight control wiring and replacement / rework of damaged wiring and components. The later should certainly affect the bottom line for Boeing and the fall in share price potentially reversing the modest gains due to the bird strike story.

Sorry, swarm should be swarf, the little bits of metal shavings left over from drilling, machining or self tapping fixtures, most likely behind panels from fitout in-situ. IOS doesn’t recognise this term! ð¤

Of course it was a bird strike that brought the Ethiopian 737Max down. What else could it be, certainly not anything that Boeing did or did not do. After all they certified the aircraft was safe to fly in the first place. The"Person in the know"would probably be the CEO who is doing everything in his power to shift the blame away from Boeing.Too much, Too fast. It will be a long time before I'll trust the any 737X, The Dreamliner or the 777X, a really long time!

OK, so it's some un-named "U.S. aviation officials" who are making a claim that is not supported by the hard evidence...

"U.S. aviation officials think a bird strike is the likely culprit in what led to erroneous sensor data fed to the anti-stall system in the Ethiopian crash, the person said. Ethiopian Airlines has said, however, that a preliminary crash investigation report showed “no evidence of any foreign object damage” such as a bird strike, to the sensor."

Sounds ever more like a desperate search to come up with an "it wasn't our fault" cause for the crash, even if the hardware shows it is probably not the case.

I believe that the management of both Boeing and the FAA are to blame for the lose of 346 lives in both of these crashes. Boeing for NOT keeping all the safety equipement in the aircraft as standard equipement, plus not training all pilots on the operations of MCAS plus not updating the flight manuals on all the aircraft. The FAA is to carry much of the blame as well for allowing Boeing to self certify their aircraft. This whole thing has been because Boeing wanted to save money at the cost of peoples safety and lives and the FAA allowed it to happen. Both the management of Boeing and the FAA should be charged and jailed. As for bird stikes, they have been an everyday thing in flying but it is not a bird strike that brought down these two plane it is the greed of both Boeing and the FAA. The FAA has lost all credibility no issue safety certification on any Boeing aircraft and a proper international safety certification organisation should be set up before Any of Boeings aircraft be allowed back into the air. This is total negligence by both Boeing and the FAA.

The FAA has lost all credibility on issuing safety certification on any aircraft and it should be replaced with a proper international safety certification organisation before any of Boeing's aircraft are allowed back into the sky

Are US aviation officials lending a hand to save Boeing ? If Boeing had been wrong in continuing with an aircraft that had fatal flaws, they have to face the music, since lives were lost twice in a short time. You can't be an aviation player if your brand-new planes keep crashing.

So when a flight crew reports repeated uncommanded nose down movements every 15 seconds how does MX know the left AOA sensor is to be replaced ? Is MCAS documented in the MX fault diagnosis and correction charts in the MX manuals ? If it is documented in the error correction section, is its operation described.

I believe this was already answered early in the Lion Air investigation / speculation. It was said that the computerised troubleshooting process was inconclusive and stopped as soon as one anomaly was found. It did not continue to verify the correct operation of the whole system, but assumed that replacement of one component resolves the fault. It is also unclear why replacement of the AoA vane did not include full calibration and testing of the system. I believe the conclusion of this part of the investigation was that the aircraft should have been grounded due to the failure to resolve a serious fault in a critical flight system. Further it was unfortunate that due to a programming error the AoA sensor disagree light fitted to the 737NG was disabled in the MAX, unless the customer had purchased the option of display of AoA values which was offers as an extra cost add-on not chosen by most airlines. This omission was allegedly known by Boeing, but withheld to be fixed in a later software update.

Hi Rob CoyThank you for your very clear and credible explanations. I think the F16 had an issue of insulation wear and intermittent shorting at locations where wiring was fed through un-grommetted holes in aluminium "firewalls"/bulkheads. Your mention of the potential for swarf (elsewhere) which can puncture insulation is also interesting. The need to calibrate and test any work on a critical system should be mandatory.

In the Lion Air case the AoA vane was replaced. The crash occurred on the 2nd flight after replacement. It seems that the investigators recovered the “faulty” sensor and also have the one that was removed from the aircraft. No word yet on the results of the analysis of these components. If the one removed from the aircraft is found to be fault free, it could have much bigger implications on the airworthiness of the aircraft.

Bird struck the only active AoA sensor? maybe, but still sounds like a fake as no official source given. Still shouldn't have downed a liner if redundancies were active and proper alerts were available.

The birds did it? For heaven sake's. The Ethiopian plane was already at 7000 ft when things went bad. Yes, you can find birds that high, but it's unlikely. US Air 1549 hit geese at 2800 feet. The big factor is Addis Ababa is no where near any large bodies of water. Even land birds need a source of water. Addis Ababa is also not on any major bird migration routes. Lyon Air and a bird strike? Much more plausible.

You would think it shouldn’t? It is a question for Boeing to answer: Why connect a hidden auto trim system to the most vulnerable piece of equipment sticking out of the nose (sides) of the aircraft? You can’t tell me that in the one of the most critical phases of flight and with all the media attention devoted to the “Sully” accident, no one pointed the what-if bird strike scenario and MCAS?

Most pilots know when they have a bird strike. Happens everyday. That a hapless bird hit the sensor and didn't get sucked into an engine, very weird. No word if bird parts were found in the engines, nor if the word "bird" is mentioned in the the cockpit recorder. Time will tell.